Use Table 16.1 to calculate ΔS^∘ for each of the following reactions: (a) 4 NH3(g)+5 O2(g) ⟶4 NO

step 1 Entropy is just a measure of randomness. So this is a numerical quantity that is determined by t

Use Table 16.1 to calculate ΔS^∘ for each of the following...

Use Table 16.1 to calculate $\Delta S^{\circ}$ for each of the following reactions: (a) $4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$ (b) $2 \mathrm{H}_{2} \mathrm{O}_{2}(l)+\mathrm{N}_{2} \mathrm{H}_{4}(l) \longrightarrow \mathrm{N}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$ (c) $\mathrm{C}(s)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$ (d) $\mathrm{CH}_{4}(g)+3 \mathrm{Cl}_{2}(g) \longrightarrow \mathrm{CHCl}_{3}(l)+3 \mathrm{HCl}(g)$

Use Table 16.1 to calculate $\Delta S^{\circ}$ for each of the following reactions:
(a) $4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)$
(b) $2 \mathrm{H}_{2} \mathrm{O}_{2}(l)+\mathrm{N}_{2} \mathrm{H}_{4}(l) \longrightarrow \mathrm{N}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$
(c) $\mathrm{C}(s)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)$
(d) $\mathrm{CH}_{4}(g)+3 \mathrm{Cl}_{2}(g) \longrightarrow \mathrm{CHCl}_{3}(l)+3 \mathrm{HCl}(g)$

Key Concepts

Standard Entropy

Standard entropy refers to the absolute entropy of a substance under specified standard conditions (often 1 atm pressure and a specified temperature, typically 298 K). In thermodynamics, this value quantifies the degree of randomness or disorder in a system and is usually measured in joules per kelvin per mole (J/(K·mol)). It provides a baseline for comparing the entropy of substances in different states or undergoing reactions.

Entropy Change Calculation in Reactions

The entropy change for a chemical reaction, ?S°, is calculated by finding the difference between the sum of the standard molar entropies of the products and the sum of the standard molar entropies of the reactants, each multiplied by their stoichiometric coefficients. This method, ?S° = ?(n·S°(products)) - ?(n·S°(reactants)), uses the fact that entropy is a state function, allowing the calculations to be done by simple arithmetic addition and subtraction.

State Function

Entropy is a state function, meaning its change depends only on the initial and final states of the system and not on the path taken. This property simplifies calculations in thermodynamics, especially for chemical reactions, because it allows the use of standard state values of substances (found in tables like Table 16.1) to accurately determine the overall change in entropy during the reaction.

Phase Dependence of Entropy

The entropy of a substance varies with its physical state; gases typically have higher entropy compared to liquids and solids due to the greater randomness and freedom of motion of their particles. Understanding the influence of phase on entropy is crucial when calculating reaction entropy changes, as the contributions to the overall entropy change from different phases can significantly affect the outcome.

Transcript

Please give Ace some feedback